CN2927023Y - Low-speed pneumatic opening structure - Google Patents

Abstract

The utility model belongs to the technical field of vehicle wind tunnel, in particular to an open low-sped wind tunnel collecting port structure, which is successively composed of a spout, a jet steam section, a collecting port and a diffusion section, wherein the spout, jet steam section and collecting port are arranged in the wind tunnel resident chamber. The utility model is characterized in that: the collecting port is combined by a collecting port body and a collecting port throat, while the collecting port body in a tapered shape is composed of three movable plates and a base plate and the collecting port throat is in a columned shape and is provided with grooves along the vertical direction and the quantity of groove is 1 to 5. The groove is the upright groove that is vertical to the axial line or the oblique groove that forms different angles with the axial line. The utility model has improved the local structure from changing the induced flow field of air-actuated acoustics so as to change the flow field structure near the collecting port, to further improve the acoustic environment, to exert the function of refraining from springing amplitude value and to improve the axial pressure gradient in the resident chamber.

Description

Open type low-speed wind tunnel collection opening structure

Technical field

The utility model belongs to the automobile wind tunnel technical field, is specifically related to a kind of open type low-speed wind tunnel collection opening structure.

Background technology

Along with developing of automobile industry, the road vehicle noise has become influences one of town dweller's life level of comfort important factors, thereby how to reduce the forward position that internal car noise also becomes research with regard to predicting and adopt an effective measure in the design phase in the developing of automobile industry process.As everyone knows, automobile wind tunnel is research and the main tool that improves the every performance of automobile, so if research automobile noise sound source, every performances such as route of transmission and internal car noise distribution, just necessarily require as the background noise of the automobile wind tunnel of instrument enough lowly, could try one's best like this and reduce because the interference that ground unrest brought produces result of study.

Since the seventies in last century, people recognize that gradually ubiquity low frequency flutter phenomenon in the automobile wind tunnel, promptly in full-scale wind tunnel, several tangible resonance peaks can appear in the wavelength coverage that is lower than 20Hz in the acoustic pressure frequency spectrum, and the frequency of these peak values and the certain relation of wind speed existence, its peak value is difficult to prediction especially, thereby the research that how to reduce low frequency flutter amplitude also becomes one of essential scientific research project gradually in the design process of automobile wind tunnel, external wind-tunnel construction experiences shows, if can not effectively suppress low frequency flutter phenomenon, be not only and bring for relevant wind tunnel experiment to seriously influence, even might destroy the structure of wind-tunnel itself.Because people are not very clear and definite to producing such flutter mechanism, thereby control method miscellaneous appearred, yet different control device stresses results for different wind-tunnel and also is not quite similar, and simultaneously its relative merits is arranged respectively also, but that ubiquitous problem has is following several:

Caused the increase of high band noise when 1) suppressing low frequency flutter amplitude;

Caused when 2) improving the acoustics field that the flow field axial pressure distribution is inhomogeneous, caused the reduction of flow field quality and wind-tunnel efficient.

So, also need the novel control device of continuous pilot development to suppress low frequency flutter amplitude at present, also to avoid or reduce above-mentioned negative effect as far as possible simultaneously, could in automobile wind tunnel, obtain good experimental situation like this.

Summary of the invention

The purpose of this utility model is to propose a kind of low frequency flutter phenomenon of existing in the wind-tunnel of can not only effectively suppressing, and also can improve the open type low-speed wind tunnel collection opening structure of flow field axial pressure gradient in the wind-tunnel simultaneously.

The open type low-speed wind tunnel collection opening structure that the utility model proposes, the open type low-speed wind tunnel is made up of spout 1, jet segment 2, collection mouth, diffuser 5 successively, spout 1, jet segment 2 and collection mouth are positioned at wind-tunnel and stay chamber 9, wherein, collect mouth and be connected to form, collect a mouthful main body 3 and be connected to form by three portable plates 6 and floor in the chamber by collecting mouthful main body 3 and collecting a mouth throat 4, tapered, collect a mouthful throat 4 and be cylindricality, collect a mouthful throat 4 and longitudinally slot, the number of groove is 1-5.

In the utility model, groove is for perpendicular to the straight trough 7 of axis or become the oblique slot 8 of different angles with axis.

When the utility model uses, guaranteeing under the constant situation of jet segment length, the width of collecting three portable plates on mouthful main body is reduced, to collect simultaneously mouthful main body along axis to the spout direction corresponding distance that moves forward, to produce corresponding gap like this between collection mouthful main body and face in the locular wall, such gap-like is similar to and will collects the different groove of throat's incision that mouth and face in the locular wall link to each other.

The utility model can effectively suppress the low frequency flutter, improve the jet segment axial pressure distribution.Use the utility model to produce different inhibition effects for low frequency flutter amplitude, can pass through calculating pressure ripple factor Cp, peak weighs noise reduction, and computing method are as follows:

$\mathrm{Cp},\mathrm{peak}=\frac{{\tilde{p}}_{\max }}{p_{\mathrm{dyn}}}=\frac{10(\frac{L_{p,\mathrm{<figure-callout\; id="20"\; label="peak"\; filenames="Y20062004302600081.png,Y20062004302600091.png"\; state="\{\{state\}\}">peak</figure-callout>}}}{20}+1g{p}_0)}{p_{\mathrm{dyn}}}$

Cp, peak---pressure fluctuation coefficient in peak value place under a certain frequency band;

---maximum fluctuation pressure value;

_Pdyn---the measuring point dynamic pressure;

p ₀---reference pressure (20 μ Pa)

Lp, peak---peak value place sound pressure level under a certain frequency band.

Generally, low frequency flutter amplitude is along with the increase of wind speed constantly increases, as shown in Figure 5, with the wind speed is that 40m/s is an example, collecting mouthful throat's fluting, its maximum noise reduction can reach 28dB, and the pressure fluctuation of jet segment also is reduced to 0.5%～2.5% from 0.5%～12.5% scope, make that the air-flow of wind tunnel experiment section is more stable, help the carrying out of aeroacoustics experiment.

The beneficial effects of the utility model: the utility model is from changing the flow field of bringing out of aeroacoustics, carried out the partial structurtes improvement, collect near a mouthful flow field structure thereby changed, and then improve acoustic enviroment, not only effectively suppress the low frequency flutter phenomenon that exists in the wind-tunnel, improve further also simultaneously that the flow field axial pressure gradient makes its variation milder in the wind-tunnel, and the pressure fluctuation value also effectively reduces, these all help carrying out in the wind-tunnel aerodynamics and noise analysis experiment, thereby obtain believable experimental data.

Description of drawings

Fig. 1 is a structural diagrams of the present utility model.

Fig. 2 collects mouthful throat's straight trough structural diagrams for the utility model.

Fig. 3 is the A-A cut-open view among Fig. 2.

Fig. 4 collects mouthful throat's oblique slot structural diagrams for the utility model.

Fig. 5 is the B-B cut-open view among Fig. 4.

Fig. 6 is a jet segment axis pressure distribution curve, and the jet segment axis pressure distribution curve when wherein dot-and-dash line is original structure, solid line are jet segment axis pressure distribution curve when using the utility model.

Fig. 7 is the noise reduction of embodiment 1, (a) is virgin state, and (b) for adopting the utility model noise reduction, here for the trench structure effect can clearly be described, ordinate of orthogonal axes does not adopt same numerical value.

Fig. 8 is the noise reduction of embodiment 2, (a) is virgin state, and (b) for adopting the utility model noise reduction, here for the trench structure effect can clearly be described, ordinate of orthogonal axes does not adopt same numerical value.

Fig. 9 is the noise reduction of embodiment 3, (a) is virgin state, and (b) for adopting the utility model noise reduction, here for the trench structure effect can clearly be described, ordinate of orthogonal axes does not adopt same numerical value.

Number in the figure: 1 is spout, and 2 is jet segment, and 3 for collecting a mouthful main body, and 4 for collecting a mouthful throat, and 5 be diffuser, and 6 is portable plate, and 7 is straight trough, and 8 is oblique slot, 9 for wind-tunnel in the chamber.

Embodiment

Further specify the utility model below by embodiment.

Embodiment 1, wind-tunnel is made up of spout, jet segment, collection mouth, diffuser successively, and spout, jet segment and collection mouth are positioned at wind-tunnel in indoor, wherein, the collection mouth is connected to form with a collection mouth throat by collecting mouthful main body, is collecting mouthful straight trough that width is 30mm of throat's incision.Take different wind speed, pressure fluctuation coefficient Cp from Fig. 7, peak figure as can be seen, near three main flutter frequencies, all played tangible noise reduction after cutting straight trough, Cp3 is that frequency has decreased by 22dB for the peak-peak that the 40-50Hz vicinity occurs among the figure, and the pressure fluctuation coefficient has dropped to 0.63% from 8.25%, decreased by 92%, the low frequency flutter amplitude that occurs for other several frequency bands also has reduction largely simultaneously.

Embodiment 2: wind-tunnel is made up of spout, jet segment, collection mouth, diffuser successively, spout, jet segment and collection mouth are positioned at wind-tunnel and stay indoor, wherein, the collection mouth is connected to form with a collection mouth throat by collecting mouthful main body, is collecting mouthful three straight troughs that width is 15mm of throat's incision.Take different wind speed, pressure fluctuation coefficient Cp from Fig. 8, peak figure as can be seen, near three main flutter frequencies, all played tangible noise reduction after cutting straight trough, Cp1 is that frequency has decreased by 23dB for the peak-peak that the 40-50Hz vicinity occurs among the figure, and the pressure fluctuation coefficient has dropped to 0.57% from 8.25%, decreased by 93%, this structure can significantly reduce the flutter peak value of several frequency bands equally as can be seen.

Embodiment 3: wind-tunnel is made up of spout, jet segment, collection mouth, diffuser successively, spout, jet segment and collection mouth are positioned at wind-tunnel and stay indoor, wherein, collect mouth and be connected to form, collecting the oblique slot that three width 15mm cut in mouthful throat by collecting mouthful main body and collecting a mouth throat.Pressure fluctuation coefficient Cp from Fig. 9, peak schemes as can be seen, and this structure can significantly reduce the flutter peak value of several frequency bands equally.

Experimental result from embodiment 1-3, the utility model has been obtained good effect, the maximum range of decrease of low frequency flutter amplitude of place, axis in chamber standard measuring point can reach 92%, particularly all played the effect that suppresses the flutter amplitude for several different flutter frequency sections, simultaneously from fluid field pressure distribution experimental result, take further to have improved behind the utility model the pressure gradient of axis in the chamber, make its variation milder, and the pressure fluctuation value also effectively reduces, these all help carrying out in the wind-tunnel aerodynamics and noise analysis experiment, thereby obtain believable experimental data.

Claims (2)

1, a kind of open type low-speed wind tunnel collection opening structure, the open type low-speed wind tunnel is made up of spout (1), jet segment (2), collection mouth, diffuser (5) successively, spout (1), jet segment (2) and collection mouth are positioned at wind-tunnel and stay chamber (9), it is characterized in that collecting mouth is connected to form by collecting mouthful main body (3) and collecting a mouthful throat (4), collecting a mouthful main body (3) is connected to form by three portable plates (6) and base plate in the chamber, tapered, collect a mouthful throat (4) and be cylindricality, collect a mouthful throat (4) and longitudinally slot, the number of groove is 1-5.

2, open type low-speed wind tunnel collection opening structure according to claim 1 is characterized in that groove is straight trough (7) perpendicular to axis or the oblique slot (8) that becomes different angles with axis.

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